1. Field of the Invention
The present invention relates to a thermal inkjet print head and, more particularly, to a thermal inkjet print head chip with at least two ink slots disposed outside two columns of heaters in which each ink slot provides ink to unilateral heaters.
2. Description of the Related Art
Thermal inkjet print heads, successively commercialized on the inkjet printer market, are operated by rapidly heating a small volume of ink, vaporizing the ink, then bubbling and ejected it through nozzle orifice by high pressure. Thus, a dot of ink can be printed onto a recording medium, such as a sheet of paper. Generally, for a one-color inkjet head chip, a single strip of ink slots is used to provide ink to two columns of firing chambers through ink channels, respectively. Also, a thin film heater is disposed inside each firing chamber to cause ink to vaporize and be ejected through one correspondingly positioned nozzle orifice.
FIG. 1A is a top view showing a conventional one-color inkjet head chip. FIG. 1B is a top view partially enlarging the firing chamber and ink slot shown in FIG. 1A. A one-color inkjet head chip 10 comprises two columns of firing chambers 12 in which the firing chambers 12 arranged in one column are not aligned, and a common ink slot 14 disposed between the two columns of firing chambers 12. Also, a plurality of ink channels 18 is provided to the firing chambers 12 respectively for connecting the firing chambers 12 and the ink slot 14. Furthermore, each firing chamber 12 comprises a nozzle orifice and a heater 16 disposed under the nozzle orifice. Therefore, an ink flow 20 moves from the ink slot 14 toward the bilateral firing chambers 12, and then the heater 16 vaporizes the ink to eject an ink dot from the nozzle orifice. Moreover, for providing a power source to the chip 10, a plurality of connecting wires 22 is patterned on the chip 10 to electrically connect the heaters 16 and a plurality of contact pads 24, respectively.
Conventionally, shaping techniques, such as etching, laser working and sandblasting are selected to form the ink slot 14. However, since the lateral space of the ink slot 14 is limited to the two columns of the firing chambers 12, the error tolerance when forming the ink slot 14 is very small, and the lateral size of the ink slot 14 cannot be further increased. This decreases the ink flow amount, speed, supply, and print quality. In addition, the connecting wire 22 is a single metal layer. When the resistance compensation is processed to give each heater 16 an equivalent wiring resistance, the line width of the metal layer is in need of modulation. Nevertheless, depending on the arranged density of the connecting wires 22, the line width of the metal layer is limited.
FIG. 2 is a top view showing a conventional multi-color inkjet head chip. A conventional multi-color inkjet head chip 26 can provide at least three colors of ink from different ink reservoirs. For example, the chip 26 comprises a first inkjet system A, a second inkjet system B and a third inkjet system C. Each of the inkjet systems A, B or C has two columns of firing chambers 12A, 12B or 12C, a common ink slot 14A, 14B and 14C, and a plurality of connecting wires 22A, 22B or 22C for electrically connecting the heaters to the contact pad 24. The firing chambers, ink slots and connecting wires within the inkjet systems A, B and C are similar to the description in FIG. 1B. Since the ink slot 14A provides ink to bilateral firing chambers 12A, the above-described problems in the one-color inkjet head chip 10 are also encountered in the multi-color inkjet head chip 20.
The present invention is an inkjet print head chip with at least two ink slots outside two columns of firing chambers. Each ink slot provides ink to unilateral heaters in one column of firing chambers.
In one preferred embodiment, An inkjet print head chip comprises: a first column of firing chambers and a second column of firing chambers in which each firing chamber comprises a heater and an ink channel; a first ink slot formed between the first column of firing chambers and the periphery of the chip to provide ink to the heaters in the first column of firing chambers; and a second ink slot formed between the second column of firing chambers and the periphery of the chip to provide ink to the heaters in the second column of firing chambers.
In another preferred embodiment, an inkjet print head chip comprises: a first column of firing chambers and a second column of firing chambers in which each firing chamber comprises a heater and an ink channel; a plurality of first ink sub-slots formed between the first column of firing chambers and the periphery of the chip to provide ink to the heaters in the first column of firing chambers; a plurality of second ink sub-slots formed between the second column of firing chambers and the periphery of the chip to provide ink to the heaters in the second column of firing chambers; and a dry film patterned on the chip to separate the first ink sub-slots and the second ink sub-slots.
In another preferred embodiment, an inkjet print head chip comprises: a first column of firing chambers and a second column of firing chambers in which each firing chamber comprises a heater and an ink channel; a first ink slot formed between the first column of firing chambers and the second column of firing chambers to provide ink to heaters in the first column of firing chambers; a second ink slot formed between the second column of firing chambers and the periphery of the chip, in which the second ink slot comprises a plurality of second ink sub-slots and each second ink sub-slot provides ink to part of heaters in the second column of firing chambers; and a dry film patterned on the entire surface of the chip to separate the second ink sub-slots.
In another embodiment, an inkjet print head chip further comprises: a plurality of connecting wires in which each connecting wire comprises at least two metal layers and an isolating layer; and a plurality of ladder-shaped connecting vias formed between the metal layers and the isolating layer.
The connecting wire goes around the region between the first column of firing chambers and the second column of firing chambers to couple to the periphery of the chip.
Accordingly, it is a principal object of the invention to improve inkflow amount, speed, supply, and print quality.
It is another object of the invention to increase the error tolerance when forming the ink slot.
Yet another object of the invention is to reduce the total area occupied by the connecting wires to compensate for the size of the ink slots.
Also, when the resistance compensation is processed to make each heater 36 have an equivalent wiring resistance, one method is to increase the line width of the metal layer and the other method is to increase the thickness of the metal layer. It is more flexible to adjust the sheet resistance of the connecting wire 42.
It is a further object of the invention to process the resistance compensation by increasing the line width of the metal layer or increasing the thickness of the metal layer.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.